Smart Prosthetic Sockets: Improved Prosthesis Comfort and Performance Through Adaptive Fluidic Flexible Matrix Composite Technology

下肢假体（如人造腿）的配合度在一天的过程中会因残肢（剩余部分）不可避免的体积损失而下降。这会导致不适、疼痛、皮肤刺激、水泡，并最终导致残肢软组织损伤。由不合适的关节窝引起的疼痛和损伤会使人衰弱并影响生活质量。该项目的目标是更好地了解体积损失的原因，评估当前最先进的假肢的体积损失，并开发一种智能假肢窝，可以适应残肢的体积损失。适应容量损失的能力将消除由于插孔不合适而造成的疼痛和伤害，并帮助用户保持高质量的生活。这项研究的结果将产生重大的社会影响，因为在美国有超过160万人没有肢体，而越南战争、伊拉克自由行动和持久自由行动冲突的服务人员构成了这一人口的很大一部分。对于这些退伍军人和服役人员来说，最常见的假肢设备问题是，这些设备佩戴起来很痛苦，并且会产生皮肤问题，这导致至少22%的设备被遗弃。通过高中、本科研究以及指导，计划中的教育努力将对学生产生广泛的影响，为他们提供将课堂上教授的分析工具应用于“现实世界”问题的独特而宝贵的经验。此外，许多物理原理和课堂例子可以直接从研究中得到说明，以便在研究者教授的本科课程中获得教育效益。教育和推广计划将通过与特殊残疾学生工程多样性和服务中心合作的K-12推广项目，对学生的学习产生广泛的影响。经股骨或经胫骨（膝盖以上或膝盖以下）截肢的患者在佩戴假肢时，残肢的体积每天都会发生变化。容积变化导致残肢在假体窝内的拟合不良，从而导致不同程度的不适、疼痛、皮肤刺激和组织损伤。本项目重点研究残肢体积变化的深层原因，测量残肢在槽内产生的变形，并采用流体柔性基质复合材料（f2mc）技术开发一种能够适应残肢体积损失的智能假肢槽。研究计划分为三个任务。第一项任务是开发新的、可靠的测量技术，用于测量使用过程中的残肢体积损失和残肢变形。残肢测量系统将是测量残肢变形的数字图像相关、测量体积变化的结构光激光扫描和测量界面压力的压阻式压力传感器的集成。第二个任务是利用在评估单侧经股截肢患者的椎窝性能的第一个任务中开发的测量系统，更好地理解椎窝性能各方面之间的关系。在残肢体积变化前后，将评估残肢的四个方面的性能：1)不戴套时残肢的尺寸和体积，2)戴套时残肢的变形，3)戴套时残肢与套之间的界面压力，4)由受试者和义肢专家对残肢的性能进行主观评估。这些测量将有助于更好地了解残肢体积损失、界面窝压力和舒适评分之间的相关性，并有助于阐明导致体积变化和残肢不适或疼痛的机制，并允许探索这四个方面表现之间的预测关系。第三项任务是开发和评估定制的f2mc智能假肢插座与人体受试者。智能插座基于一项由研究人员开发的新技术，可以用作具有独特和高度可定制的形状、尺寸和机械性能的执行器，并且具有低功耗要求。f2mc“晶圆”的关键部件是围绕柔性管的多层定向高性能碳纤维，将管/纤维保持在所需形状/配置的弹性铸件，以及管道中的空气或水等内部工作流体。f2mc技术是通过对内部工作流体加压来驱动的，这将导致晶圆增厚。在加压时，晶圆的体积可以增加300%以上，使用简单的阀门控制，其刚度比高达56，并且可以制造成各种形状和配置，可以专门为用户量身定制，从而独特地适应残肢的体积损失，提高插座的舒适度。将通过台式测试和单侧经股动脉截肢患者评估椎弓根的性能。在为截肢者定制和优化智能插座后，插座的性能将与受试者当前的插座悬挂方法进行比较。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The fit of a lower limb prosthesis (e.g. an artificial leg) degrades over the course of a day due to unavoidable volume loss of the residual (remaining part of) the limb. This can lead to discomfort, pain, skin irritation, blisters, and eventually soft tissue injuries on the residual limb. The associated pain and injury caused by poor socket fit can become debilitating and impair quality of life. The goal of this project is to develop a better understanding of the causes of volume loss, evaluate volume loss in current state-of-the-art prostheses, and develop a smart prosthetic socket that can accommodate for volume loss of the residual limb. The ability to accommodate for volume loss will eliminate the pain and injury due to poor socket fit and help users maintain a high quality of life. The results of this research will have significant societal impact as more than 1.6 million people in the US are living without a limb, and service members of the Vietnam War and Operation Iraqi Freedom and Operation Enduring Freedom conflicts make up a significant portion of that population. The most common prosthetic device problems for these veterans and service members are that the devices are painful to wear and create skin problems, which leads to at least 22% total device abandonment. The planned educational efforts through high school, undergraduate research, as well as mentorship, will have a broad impact on the students by providing them with the unique and valuable experience of applying analysis tools taught in the classroom to a "real-world" problem. Additionally, numerous physical principles and classroom examples can be illustrated directly from the research for educational benefit in undergraduate courses taught by the investigators. The education and outreach plan will provide a broad impact on students' learning through K-12 outreach programs in collaboration with the Center for the Enhancement of Engineering Diversity and Services for Students with Special Disabilities.Individuals with transfemoral or transtibial (above the knee or below the knee) amputations experience daily changes in the volume of residual limbs while wearing prosthetic limbs. The volume changes lead to poor fitting of the residual limb in the prosthetic socket, and consequently to various levels of discomfort, pain, skin irritation and tissue damage. This project is focused on studying the underlying reasons for volume change in the residual limbs, measuring the resulting limb deformations in the socket, and developing a smart prosthetic socket employing fluidic flexible matrix composite (f2mc) technology that can accommodate for volume loss of the residual limb. The Research Plan is organized under three tasks. The FIRST Task is to develop new, robust measurement techniques for measuring residual limb volume loss and limb deformation during use. The residual limb measurement system will be an integration of digital image correlation for measuring limb deformation, structured light laser scanning for measuring volume change, and piezoresistive pressure sensors for measuring interfacial pressures. The SECOND Task is to achieve a greater understanding of the relationship between facets of socket performance using the measurement system developed under the first task in assessing socket performance in subjects with unilateral transfemoral amputation. Four facets of socket performance will be evaluated before and after volume change of the residual limb: 1) dimensions and volume of the residual limb when not wearing the socket, 2) limb deformation when wearing the socket, 3) interfacial pressure between the socket and the residual limb when wearing the socket, and 4) subjective assessments of socket performance provided by both subjects and prosthetists. These measurements will provide a greater understanding of the correlation between residual limb volume loss, interfacial socket pressure, and comfort score and help clarify the mechanisms that lead to volume change, and residual limb discomfort or pain, and allow predictive relationships between these four facets of performance to be explored. The THIRD Task is to develop and evaluate customized f2mc smart prosthetic sockets with human subjects. The smart sockets are based upon a novel technology, developed by the investigators, that can be used as an actuator with unique and highly-customizable shapes, sizes, and mechanical properties and that have low power requirements. Key components of the f2mc "wafers" are multiple layers of oriented, high performance carbon fibers surrounding a flexible tube, an elastic casting to hold the tubing/fibers in a desired shape/configuration, and an internal working fluid, such as air or water in the tubing. The f2mc technology is actuated by pressurizing the internal working fluid, which will lead to wafer thickening. The wafers can achieve more than 300% increase in volume when pressurized, exhibit stiffness ratios as high as 56 using simple valve control and be fabricated into a variety of shapes and configurations that can be tailored specifically for the user and thus uniquely accommodate for volume loss of the residual limb and improve socket comfort. Socket performance will be evaluated via benchtop testing and in human subjects with unilateral transfemoral amputation. After the smart sockets are customized and optimized for the amputees, the socket's performance will be compared to the subject's current socket suspension method.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.